Spinneret for the production of viscose filaments



Patented Dec. 27, 1949 SPINNERET FOR THE PRODUCTION OF VISCOSE FILAMENTS Dan B.- Wicker, Dunbar, and Elvin L. Coe', Nitro,

W'. Va., assignors to American Viscose Corporation, Wilmington, ,Del., a corporation of Delaware No D aw n ;-v App at on. January- .3:, 1945,.

Serial No. 571,193

4 Glaims.

This invention relates to improvements in the manufacture of artificial fibers from viscose.

Artificial fibers comprising regenerated cellulose from viscose are. obtainedv by the. Wet spinning method, that is the viscose is spun through a spinneret into an acidspinning bath in whichjindividual streams of viscose-emerging from the spinneret are coagulated and regenerated. Under such conditions, the acid; bath contains a large amount of suspended gas bubbles. Ordinarily, the. spinneret-has a comparatively low orifice area density and the gas bubbles do not interfere with the orderly and" continuous progress of the individual' streams of viscose away from the face of; the spinneret and the streams are separately acted upon by the bath and coagulated. However, in the manufacture of filaments which are destined for cutting, intolstaple. fibers, it is desirable to spin a great many filaments from a single spinneret and collect thebundle of filaments in the form of a long tow which :is' thenfed to. a staple fiber cuttingv mechanism. The spinnerets are made from precious metals such as platinum or the like and, for obvious reasons of economy, must be kept as small as possible which, in the case of spinning a very-large number of filaments from a single spinneret, requires a high orifice area density; When. viscose isspun through such spinnerets having. an orifice area densityso-high that the orifice area density factor K isgreater than 809 when. determined in. accordance with the following general formula KS AD, D- A or its equivalent, K-

where D=orifice density, orifices/sq. in. S=periphery of jet face in inches, and A=area of jet face in sq. inches.

it is a common observation that the gas bubbles which permeate the bath are attracted to and tend to adhere to or cling to the face. Under those conditions, the progress of the acid to the individual streams of viscose issuing from the spinneret away from the face into the bath is seriously hampered. The bubbles clinging to the exceedingly small unperforated portions of the face which exist between the densely packed orifices interfere with acid distribution and permit a multiplicity of the streams of raw viscose to. come together without having been coagulated. As they are drawn through the spinning bath by the action of the godet wheel, the merged streams are coagulated and cemented together to form excessively large filaments or splinters which occur haphazardly through t he final bundle. The phenomenon of, gas. bubble adherence. to the face of, they spinneretjij extremely troublesome. necessitating frequent discontinuance of the. spinning operation .and manual dislodgement of the gas bubbles, and requiring the spinning of a large number of endsin order toobta-in a tow haying sufficient average. total denier over a long period of time. Theypnoblem. is, encountered only in those instances when the spinneretemp y d has a face of small diameter and an orifice area density such that according to the foregoing formula, the value of the factor K is greater than 800. No satisfactory solution of the Problem has been propounded heretofore- This invention has as an object improvements in the spinning of artificial fibers through spinnerets having high orifice area density. A further object isato :alter the interfacial tensions ex:- isting at. the face of such. spinnerets in acidspinping baths to prevent: the. adherence of gas. bubbles. to the. face. Anotherobject is to coat the: face. of such a spinneret with a substance. Which will repel gas bubbles andl'nelltralize their; tend-- ency to adhere to the surface thereof. Other objects will appear hereinafter- These objectives. are accomplished by coating the spinneret face with a film. of. a saponifiable. oil, mono-esters of fatty acids of the type. which occur naturally in the fatty oils with glycerol, and. mono-esters of certain of. suc fa ty acids with ethylene and diethylene glycols. Although the saponii'iable oils and glycerides of fatty acids derivable therefrom are alt efi'ective, generally speaking, as protective agents for inhibiting the tendency of gas bubbles to become attached to the spinneret face, the esters of the acids with glycol and. diethylene glycol show a, high degree of specificity in this regard. Thus, whereas diethylene glycol mono-oleate and mono-myristate have been found effective, diethylene glycol mono-laurate has been found ineffective. Likewise, glycol mono-laurate is ineffective while, on the other hand, glycol mono-oleate has been found to be effective.

Representative substances which are efficacious in protecting the face of spinnerets having a high orifice area density are castor oil, olive oil, glycerol mono-oleate, glycerol mono-ricin0- leate, diethylene glycol mono-oleate, glycol monooleate, diethylene glycol mono-myristate, and glycerol mono-laurate. Where the esters are used, the invention is not restricted to employment of the pure compounds themselves, but includes mixtures thereof, and also such mixed compounds as the technical grades supplied commercially by various manufacturers under the trade names of the individual compounds.

The mentioned substances may be used with advantage in spinning viscose through spinnerets constructed of or having a face of gold, tantalum, platinum, and various alloys. The substances which are generally of oily, sometimes viscid consistency, may be applied by wiping the spinneret face with a cloth or sponge carrying the particular substance which is utilized. The compounds show a satisfactory degree of effectiveness over a sufficiently prolonged period to permit the obtention of satisfactory tows which are substantially free of splinters, without requiring the spinning of a large number of ends, and do not exert any deleterious efiect on the filaments obtained by extruding viscose into the spinning bath. The orifices of the spinneret may be distributed in the conventional circular area, but it is to be understood, of course, that the invention is not limited to spinnerets having an orifice area of any particular shape.

The following examples will illustrate the invention.

Example I Viscose was spun through a circular metal spinneret having a diameter of two inches and an orifice area density factor K of 950 when determined by the formula KS "'T1' where D=orifice density, orifices/sq. in. S=6.283 A=3.14

Example II The procedure was the same as in Example I except that the factor K was 850 and the outer face of the spirmeret was coated with glycerol mono-oleate.

Example III The procedure was identical with that described in Example I, with the exception that the face of the spinneret was coated with glycerol mono-ricinoleate.

While preferred embodiments of the invention have been shown, it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined by the appended claims.

We claim:

1. A precious metal spinneret having an orifice area density factor K greater than 800 determined by the general formula K=AD/S where D is the orifice density of the spinneret expressed as orifices per square inch, S is the periphery of the spinneret face in inches and A is the area of the spinneret face in square inches, the outer surface of the orificed spinneret face being coated with an oily substance selected from the group consisting of glycol mono-oleate, diethylene glycol-mono-oleate, diethylene glycol mono-myristate, and mono-esters of fatty acids of the type derivable from saponifiable vegetable oils with glycerol.

2. The spinneret of claim 1 in which K has a value up to 950.

3. The spinneret of claim 2 in which the substance is glycerol mono-oleate.

4. A precious metal spinneret having an orifice area density factor K greater than 800 determined by the general formula K=AD/S where D is the orifice density of the spinneret expressed as orifices per square inch, S is the periphery of the spinneret face in inches and A is the area of the spinneret face in square inches, the outer surface of the orificed spinneret face being coated with glycerol mono-ricinoleate.

DAN B. WICKER. ELVIN L. COE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,826,718 Barthelemy Oct. 13, 1931 1,901,658 Ladrette Mar. 14, 1933 1,959,930 Schmidt et al May 22, 1934 2,100,581 Weeldenburg Nov. 30, 1937 2,273,638 Graves Feb. 1'7, 1942 2,284,154 Barthelemy et al. Aug. 25, 1942 FOREIGN PATENTS Number Country Date 273,647 Great Britain Sept. 22, 1927 

